Ultrastructural and morphometric analyses of human cementoblasts and periodontal fibroblasts

In order to elucidate the cytological characteristics of human cementoblasts which distinguish them from periodontal fibroblasts, the periodontal ligament and gingival connective tissue attached to 37 extracted teeth from 27 patients (ages 10-67) were analyzed by electron microscopy coupled with a morphometric procedure. The cementoblasts largely consisted of either immature or resting types of collagen-producing cells (CPC), both of which were poor in the rough endoplasmic reticulum and Golgi complex; these organelles were well-developed in the relatively less common active cementoblasts. The cementoblasts consistently revealed a higher mean-volume-density per tissue unit than the fibroblasts and sometimes were grouped into clusters with the formation of junctional apparatuses. The relative volume of glycogen particles per cytoplasm was significantly higher in the cementoblasts, whereas the rough endoplasmic reticulum was higher in the fibroblasts. From the present study, it is suggested that the cementoblasts are functionally less active CPC than the periodontal fibroblasts.